1. Field of the Invention
The present invention relates to zippers and more particularly, to a roller zipper slide for zip fastener, which employs a rolling contact technique to substitute for conventional surface friction designs, improving sliding mobility, reducing zipper teeth wear and prolonging zipper slide lifespan.
2. Description of the Related Art
The basic functional design of a zipper slide derives from rotating engagement between gears. The left series of teeth and right series of teeth of a zip fastener are regarded as two equal length flexible tooth bar. A zipper slide is movable by a pull tab to interlock or separate left and right series of teeth. If the protruding upper faces of the left series of teeth are stopped against the protruding upper faces of the right series of teeth during movement of the zipper slide to interlock the left and right series of teeth, much friction resistance will be produced, interfering sliding mobility. Further, if the protruding upper faces of the left and right series of teeth are not kept in horizontal during interlocking, the teeth may be not interlocked positively. To enhance sliding mobility, the internal dimension of a zipper slide may be corrected. However, because different zip fastener manufacturers provide different specifications of zip fastener component parts, all commercial zip fastener components are not interchangeable. There are tolerance control on zipper slide specifications and interlocking teeth. However, when the zipper slide of a zip fastener used in a bag or tent is moved to the head end or tail end, biasing of the pull tab in a particular angle may cause the zipper slide to rub against the interlocking teeth or zipper tapes, causing a zipper tooth or zipper tape damage and shortening the lifespan of the zip fastener,